The present invention relates to the field of binding a bundle of wires or cables or the like by means of a self-locking cable tie having an apertured head including a movable pawl cooperating with a tail part having a toothed structure.
More in particular the present invention relates to a tool for installing and fastening a cable tie strap in an automatic way, wherein the tool is powered by means of compressed air, and tie straps are automatically delivered to the installation tool by means of a flow of compressed air from an automatic dispenser at each operation of the installation tool.
Automatic cable tie installation tools comprising means for grasping a bundle of cables or the like, and including means for propelling a tie strap along a closed path around the grasped bundle of cables or the like, and means for tightening the tie strap around the bundle of cables and for cutting an excess part of the tail of a tie strap are known in the art.
Examples of automatic cable tie installation tools according to the art are disclosed for example in U.S. Pat. No. 3,946,769 issued on Mar. 30, 1976 and assigned to Panduit Corporation, USA; U.S. Pat. No. 3,515,178 issued on Jun. 2, 1970 and assigned to Thomas & Betts Corporation, USA; U.S. Pat. No. 5,205,328 issued on Apr. 27, 1993 and assigned to Panduit Corp., USA, and others.
The problem of lacing bundles of wires or cables or the like has been recognized for a long time in the electrical and electronics industry.
Prior to the advent of cable tie straps of the above mentioned kind, the lacing of cables or the like was performed by hand with lacing cords, lacing spirals, etc. The introduction several years ago of tie straps having an apertured head and a toothed tail arranged to engage a retaining pawl provided in the aperture of the apertured head has contributed to alleviate the production costs, and concurrently with the development of cable tie straps of the concerned kind, installation tools have been developed to further increase the productivity of an operator and to further reduce the consequent costs.
A consideration of automatic cable tie installation tools as it results, among others, from the specification of the above-identified patents makes clear that there are still many problems that leave open the way to improvements both in the tie straps themselves and in the automatic cable tie installation tools.
A first problem lies in the fact that the tie straps of the kind in question for use in automatic tools have an asymmetrical structure that leads to problems in propelling a tie strap towards the installation mechanisms that are particularly serious when a separate tie strap dispenser has to cooperate with the installation tool because the correct orientation must be maintained along a propulsion conduit leading from a dispenser to the installation tool.
Symmetrical tie straps are now disclosed in U.S. patent application Ser. No. 08/689,466, filed on Aug. 6, 1996, entitled: "A SELF LOCKING CABLE TIE STRAP WITH SYMMETRICAL STRUCTURE".
Although these tie straps facilitate orientation of the tail with respect to the head, automatic installation tools that take advantage of the improved cable tie straps mentioned above are not known.
Other problems are connected with the personal safety or an operator when using automatic installation tools that customarily have power actuated jaws for positioning and installing a tie strap around a bundle of cables or the like, that can injure the fingers of a careless operator or "pinch" or even cut a wire or cable in the nip of the closing jaws, with the result that an entire bundle of cables has to be scrapped, with obvious consequences.
Another problem encountered with installation tools of the known prior art consists in the fact that for the sequential installation of straps one after the other in a long span of a bundle of wires or cables, for each installation of a strap the whole cycle has to be repeated with a consequent loss of time.
Accordingly an object of the present invention is to provide an automatic tie strap installation tool that makes it possible to overcome the inconveniences shown in tools of this kind according to the prior art.
According to the present invention there is provided an automatic cable tie installation tool, comprising:
A frame with a handle with manual trigger means.
A movable jaw for grasping a bundle of cables or the like to be tied with a tie strap.
Means interconnecting said trigger means and said jaw, for moving the jaw in engagement with said bundle of cables with the manual force of the operator.
Means that can be actuated at the end of said engagement operation for retracting said jaw to define a substantially closed path for a cable tie.
Means for "shooting" a cable tie having a random orientation towards said closed path, associated with means for braking and correctly orienting said cable tie strap before entering of the same into said closed path.
Means for pushing said cable tie along said closed path and for engaging the tail of the cable tie after the passage thereof through said apertured head so that the cable tie is tightened around the bundle of cables or the like.
Means for grasping the tail of a cable tie strap after it passes through the apertured head, so that the cable tie is tightened around the bundle of cables or the like.
Means cooperating with said third power means, to sense when a desired tightening of the cable tie has been reached, and to actuate means to drive cutting means for severing the excess of said tail of said cable tie strap.
Means for returning said first means to their rest condition in order to open and release said jaw and to reposition said second means in their rest position, ready for a new operation.
Still according to the present invention there are provided means for repeating an installation operation for a plurality of tie straps in sequence without the execution of a complete cycle, i.e. maintaining closed the movable jaw while the tool is shifted along a span of a bundle of wires or cables that requires the installation of a plurality of tie straps.
Other characteristics, features and advantages of the automatic cable tie installation tool according to the invention will become clear from the following description, given only as a non-limiting example and with reference to the attached drawings.